Middleport Calcining Works is located in Stoke on Trent in Staffordshire and is situated on the east bank of the Trent and Mersey canal. The works processed flint and cattle bone into a fine white powder known as bone ash.
The Middleport Calcining Works were built in the 1870's when bone china became popular. Bone china is a type of porcelain developed by Josiah Spode in the 1800's which uses calcined cattle bone called bone ash, as a major component.
The site has changed from its original form due to changes in the processes involved in producing bone ash. The kiln is an important step in the processing of bone ash and the rectangular kiln is now a grade II listed feature on site. The kiln is a tall tapering rectangular structure which houses two square flues over circular metal furnace. A lean-to provided a dry working area around the furnace mouth for firing and unloading the calcined flint and bone.
The North West range of buildings housed the boiler, engine room and grinding mill, all appear to have been built as a single unit. In 1878 the canal side was still a wharf but by 1900 this area was completely filled with a two storey range which was probably used for loading/unloading and storage of raw materials and finished powders direct from the Trent and Mersey canal.
The South East range of buildings have been altered and no longer resemble their original form. The ground floor area is the oldest section built in ‘fire proof’ construction with shallow brick arches resting on cast iron metal girders and cast iron metal posts. We believe this construction method was for strength rather than fire protection. The first floor is part of the original construction and contained both settlement and drying tanks so that ground materials could be distributed in cut blocks or further processed into powders. Its not possible to determine the exact location of these processes within the fragmented remains of this building, it is evident that a second floor level was added to this range of buildings.
The buildings and kiln are now derelict and the future is unknown.